The present disclosure relates to rotating electrical machine control devices that drivingly control an alternating current (AC) rotating electrical machine.
For example, in electric vehicles, hybrid vehicles, etc., an inverter that converts electric power between a direct current (DC) and an alternating current (AC) is disposed between an AC rotating electrical machine that drives wheels and a high voltage DC power supply. In many cases, switching of the inverter is controlled by an inverter control device that operates with electric power supplied from a low voltage DC power supply that outputs a lower voltage than the high voltage DC power supply. In some cases, a switch device (contactor) is disposed between the high voltage DC power supply and the inverter. When the contacts of the contactor are closed, the contactor is conductive, so that the high voltage DC power supply and the inverter (and the rotating electrical machine) are electrically connected to each other. When the contacts are open, the contactor is non-conductive, so that the high voltage DC power supply and the inverter (and the rotating electrical machine) are electrically disconnected from each other.
If an overcurrent, an overvoltage, etc. occurs in the inverter, the inverter control device performs fail-safe control to cause the inverter to perform a switching operation. For example, the inverter control device performs active short-circuit control (zero vector sequence control (ZVS control)) in which some of switching elements are turned on so that a current circulates between the rotating electrical machine and the inverter. For example, Japanese Patent Application Publication No. 2011-55582 (JP 2011-55582 A) discloses a control method in which all of switching elements in the upper stage of the inverter are turned off and one or more of switching elements in the lower stage of the inverter are turned on (Japanese Patent Application Publication No. 2011-55582: FIG. 2, paragraphs 158, 159, 165, etc.).
However, there is a case where the low voltage DC power supply stops and wire disconnection, opening of a connector such as a relay, short-circuit, etc. occurs in connection between the low voltage DC power supply and the inverter control device. In such a case, it may not be possible to cause the inverter to appropriately perform the above fail-safe operation.